Spectral, biological screening of metal chelates of chalcone based Schiff bases of N-(3-aminopropyl) imidazole

Tridentate chelate complexes of Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the chalcone based ligands 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-(phenylallyl)]phenol(HL1), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-p-tolylallyl]phenol(HL2), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-4-nitrophenylallyl]phenol(HL3). Microanalytical data, UV-vis spectrophotometric method, magnetic susceptibility measurements, IR, 1H NMR, Mass, and EPR techniques were used to characterize the structure of chelates. The electronic absorption spectra and magnetic susceptibility measurements suggest a distorted square planar geometry for the copper(II) ion. The other metal complexes show distorted tetrahedral geometry. The coordination of the ligands with metal(II) ions was further confirmed by solution fluorescence spectrum. The antimicrobial activity of the ligands and metal(II) complexes against the species Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albigans and Aspergillus niger has been carried out and compared. The electrochemical behavior of copper(II) complex is studied by cyclic voltammetry.

chalcone based Schiff base ligands (HL1–HL3) and their Co(II), Ni(II), Cu(II). Zn(II) complexes have been synthesized and characterized. The metal(II) ions are coordinated to azomethinc nitrogen, imidazole nitrogen and phenolic oxygen. Copper(II) complexes show distorted square planar and Co(II), Ni(II) and Zn(II) complexes show distorted tetrahedral geometry. The Schiff bases and their complexes were potentially active towards all microbial stains except E. coli. The fungal studies against Candida albigans show promising results.Figure optionsDownload as PowerPoint slideHighlights
► Participation of imidazole nitrogen (N-3) in coordination of metal(II)complexes of chalcone based Schiff bases.
► Distorted square planar geometry has been proposed for Cu(II) complexes.
► Distorted tetrahedral geometry has been proposed for Co(II), Ni(II) and Zn(II) complexes.
► Comparison of biological activity of nitro and bromo substituted Schiff bases and their complexes.